Thermocopying

ABSTRACT

A dispersion of solid hydrophobic thermoplastic polymer particles in a continuous phase of a hydrophilic binder on a support is imagewise exposed to heat. An aqueous solution of a colorant is diffused through the hydrophilic areas of the dispersion layer which were not exposed to heat and the support is imagewise colored.

llnllem States Patent Inventor Marcel Nicolas Vrartclten 11love, Belgium App]. No. 677,764 Filed Oct. 24, 1967 Patented Oct. 26, 1971 Assignee Gevaert-Agfa,N.V.

Mortsel, Belgium Priority Get. 24, 1966 Great Britain 47627/66 TlIlElRMOCOPl/IING 17 Claims, No Drawings US. Cl 96/13, 96/27,96/36,250/65.1,117/36.7,117/36.8 lnt. Cl G03c 7/16, G03c 5/04 Field of Search 96/27, 36,

Van Der Grinten Bulletin, Thermographic Writing and Copying Methods and Materials," No. 6 8, Aug. 1, 1963, pp. 1- 6 Primary ExaminerGeorge F. Lesmes Assistant Examiner-11. E. Martin Attorneywilliam J. Daniel ABSTRACT: A dispersion of solid hydrophobic thermoplastic polymer particles in a continuous phase of a hydrophilic binder on a support is imagewise exposed to heat. An aqueous solution ofa colorant is diffused through the hydrophilic areas of the dispersion layer which were not exposed to heat and the support is imagewise colored.

The present invention relates to methods for recording and reproducing information and to materials for use in said methods. The invention more particularly but not exclusively relates to a method for recording imagewise or recordwise modulated light energy, which is transformed into heat in a heat-sensitive recording material.

It has been proposed to record information by informationwise heating a recording layer composed so that under the action of such heating it undergoes a change in water permeability. ln consequence of the informationwise heating the information is therefore recorded in terms of a difference in the water permeabilities of different areas of the recording layer.

Certain recording materials for use in that way, and recording processes wherein such materials are used, are described and claimed, a.o. in Belgian Pat. No. 656,713 and in the published Dutch Pat. application No. 6,606,719. Such recording materials have recorded layers comprising a network of hydrophobic thermoplastic polymer particles dispersed in a continuous phase consisting of a hydrophilic binder.

Other recording materials for use in that way are described in the United Kingdom Pat. application 47,626/66 filed on even date herewith. Such recording materials comprise a recording layer containing a binder and a liquid material and/or solid material dispersed in said binder, the liquid and/or solid material being more hydrophobic than the binder and at least partly forming compatible mixture with the binder upon heating, whereby the light-transparency of said compatible mixture is higher than that of the dispersion before heating.

The required ratio of hydrophobic material to hydrophilic binder in the recording layer depends on the degree of disslution of the particular hydrophilic and hydrophobic ingredients into each other on heating, as well as on the desired degree of differentiation. Preferably the ratio by weight of said more hydrophobic dispersed material to hydrophilic binder is at least 1:4 and at most 25:1. As more hydrophobic materials preferably substances having a melting point between and 250 C. above room temperature are used. In that respect waxes and waxlilte substances are preferred which form with a hydrophilic binder a compatible melt on heating.

Other recording materials wherein information can be recorded in terms of a differential water permeability by informationwise heating are described in the published Dutch Pat. applications 6,516,925 and 6,601,617. 1n the latter case a polyvinyl alcohol polymer comprising at least 95 percent of vinyl alcohol units is described as having the property of becoming less soluble in water by heating.

Still other recording materials in which information can be recorded in terms of a differential water permeability by informationwise heating a recording layer are described in the United Kingdom Pat. No. 985,933 and the published Dutch Pat. application 6,608,504. In the latter recording materials the recording layer is composed wholly or mainly of gelatin, which becomes more water soluble and consequently more water permeable when sufficiently heated.

An interesting development of this principle of recording information is the use of recording material that contains distributed in the recording layer one or more substances capable of absorbing electromagnetic radiation, e.g., infrared radiation and/or visible light, and in which the recording layer becomes heated by virtue of radiation absorbed by such substance(s) when the recording material is irradiated. The aforesaid earlier Pat. applications and specifications include descriptions of recording materials useful in that way. Further, such materials are described in the published Dutch lPat. application 6,606,719. When a radiation-absorbing substance is distributed in the recording layer, the informationwise heating of the recording layer, which brings about the differentiation in water permeability or water solubility, can be achieved by informationwise exposing the recording material to sufficient radiation of appropriate type.

The presence of the radiation-absorbing substance(s) in the aforesaid recording materials makes the record visible, provided the recording material is treated, following the informationwise heating, to remove the recording layer selectively in dependence on the water permeability pattern. lt will be apparent, however, that the result of forming a visible record in that way is that the color and optical density of the record are determined by the substance(s) used for absorbing the electromagnetic radiation.

It has been found now that it is possible to use the permeability pattern in the aforesaid recording materials for creating a chemically or physically detectable change in a layer or sup port laying in water permeable relationship under the recording layer and to integrally remove that recording layer after said change has been obtained.

More particularly has been found a method of recording and reproducing information, which comprises the following steps:

1. the informationwise heating of a recording material comprising a recording layer in which informationwise heating can be recorded in terms of a differential water permeability and wherein said recording layer is applied to a support or interlayer of which the physical and/or chemical properties can be altered by means of substances capable of penetrating into the more permeable portions of the recording layer,

2. treating the recording layer after its informationwise heating with a substance or composition that penetrates into the more permeable portions of the recording layer and effeels a physical and/or chemical change in the underlaying support or layer, and

3. integrally removing the recording layer, e.g., by rubbing it and moistening it with a liquid.

Said processing technique containing the one-step integral removal of the heat-sensitive recording layer, provides copies of an improved quality more particularly when applied in combination with an exposure technique wherein said layer is internally heated by light absorbed in (a) substance(s) dis tributed therein. ln that technique the intensity and duration of the imagewise irradiation with electromagnetic radiation of the type of infrared and/or visible light is such that in consequence of the said absorption of light and the thereby generated heat in said surface layer a record is formed in terms of a difference in the water permeability of different areas of said surface layer.

By the integral removal of the recording layer containing said light-absorbing substances after the formation of a desired visible change in the support or layer laying beneath the recording layer, a final image with improved optical quality is obtained since the overall grey tone or color due to the nondifferential presence of the light-absorbing substances in the recording layer no longer masks or dissimulates the image in the underlaying support or layer.

According to a preferred embodiment the recording layer is applied as a surface layer or top layer and contains dispersed in a hydrophilic binder hydrophobic thermoplastic polymer particles, which are solid at room temperature. 1n order to ob tain particularly good results a recording material is used comprising at least one heat-sensitive layer undergoing a decrease in permeability to water when heated, and incorporating particles composed wholly or mainly of a hydrophobic thermoplastic polymer solid at room temperature. Said layer comprises preferably a major part by volume of a dispersion containing said particles in a hydrophilic binder in a weight ratio greater than 1:1, as well as an amount of a substance that absorbs infrared radiation and/or visible light and converts a substantial part thereof into heat.

Suitable hydrophilic binders, thermosplastic polymers and light-absorbing substances for preparing such a recording material are described in published Dutch Pat. application 6,606,719.

Preferably, the heat-sensitive layer used in the present invention incorporates particles, which are solid at room temperature, of a hydrophobic thermoplastic polymeric material, which has been dispersed in an aqueous medium by means ofa dispersing agent. The sensitivity to heat of the recording layers depends on the concentration of the said thermoplastic hydrophobic polymer particles in the hydrophilic binder and particularly suited compositions contain these particles in a weight ratio of at least 3:2.

The said recording layer for reason of heat-sensitivity preferably consists for at least 50 percent of volume of the dispersion of said hydrophobic polymer particles in the hydrophilic binder. As a matter of course the heat sensitivity of the recording layer also depends on the concentration of the lightabsorbing heat-generating substance(s) and its (their) absorption spectrum. Preference is given to dark substances, which absorb electromagnetic radiation in a visible-part of the electromagnetic spectrum as large as possible, and preferably in the infrared region (wavelength beyond 700 nm). If the recording material is to be used in a reflex exposure process, the concentration of heat-generating substances should preferably be such that the optical density to copying light is comprised between 0.2 and 0.8. Recording materials applied in direct exposure preferably possess an optical density of at least 1. The sensitivity of the preferred heat-sensitive recording layers is such that an exposure energy of only 0.3 watt.sec./sq.cm. is required for producing a practically useful differentiation in water permeability.

The thermoplastic polymeric material, which is dispersed in the hydrophilic binder, may comprise a single polymer or a mixture of polymers; hereafter for convenience reference is simply made to the (or a) polymer.

The hydrophobic thermoplastic polymer particles dispersed in the hydrophilic binder of the recording layer preferably soften between 10 and 200 C. above room temperature. As examples of suitable polymers may be cited polymers having a melting point or a glass-transition temperature between 10 and 200 C. above room temperature. Particularly suitable polymers are polyethylene and polyvinylidene chloride having a melting point of 110 and 190 C. respectively, and the following polymers with their respective glass-transition temperatures polystyrene (100 C.), polymethyl methacrylate (comprised between 70 and 105 C. polyethyl methacrylate (50 C.), polyvinylchloride (near 70 C.), polyacrylonitrile (near 100 C.), and poly (N-vinylearbazole) (200 C.). These polymers are preferably applied from a latex.

Polymers possessing a molecular weight in the range of 5,000 to 1,000,000 are preferred. With polyethylene possessing a molecular weight of 15,000 to 50,000 very good results are obtained.

For the preparation of latices, e.g., by emulsion polymerisation and other techniques, we refer to the published Pat. application No. 6,606,719.

A dispersing and/or wetting agent is employed in the formation of the latex and this means that dispersing and/or wetting agent may be present in the recording layer, in an amount of 5 to 30 percent by weight based on the weight of the polymer present. The attainment of optimum results in the recording method may depend upon the presence of such a dispersing and/or wetting agent in the layer, although the reason for the excellence of the results obtained in the most favorable tests, which will be exemplified later, is not known with certainty.

For all commercial purposes the surface recording layer must sufficiently cohere and adhere to the underlaying layer or support and this means that the hydrophobic polymer particles should preferably be present in a binder, although when treating the recording material with care useful results can be obtained with a binderless latex layer wherein the solid latex particles are held together with their wetting or dispersing agent, and adheres to the underlying coating or support.

The particle size of the polymer particles is preferably between 0.0144 and 50p.

Hydrophilic binding agents suitable for application in the recording layer containing hydrophobic thermoplastic polymer particles can be found in the class of hydrophilic natural colloids and synthetic hydrophilic polymers.

Particularly suited hydrophilic binding agents of the water soluble type are, e.g. hydrophilic colloids such as gelatin,

glue, casein, zein, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose, carboxymethylhydroxyethylcellulose, hydroxyethyl-starch, gum arabic, sucrose octa-acetate, sodium alginate, po1y(N-vinylpyrrolidone), polyvinyl alcohol, polyethylene oxide, vinyl polymers containing carboxylic acid and/or sulfonic acid groups and such vinyl polymers containing ammonium groups.

The recording layer may contain a softening agent for the hydrophilic binder. Thus, e.g., urea and potassium thiocyanate can be used as softening agents for gelatin.

In the surface layer the said substances or a mixture of substances for yielding heat energy by the absorption of electromagnetic radiation may be in dissolved or particulate form. Finely divided black or dark colored pigments or dyes are very suitable. Such substance or mixture of substances may be present in the polymer particles but are normally present in dispersed state in the hydrophilic binder. The light-absorbing substance or substances may be present in an amount up to 50 percent by weight of the solid content of the surface recording layer.

Pigments suited for use according to the present invention and which convert infrared and visible light into heat are, e.g., carbon black, graphite, oxides or sulfides of heavy metals, particularly of those heavy metals having an atomic weight between 45 and 210, such as manganese or lead sulfide or these heavy metals themselves in finely divided state such as silver, bismuth, lead, iron, cobalt or nickel. At present, preference is for carbon black as light-absorbing material in carrying out the invention. Black or deep black colored pigments are preferred when no colors have to be reproduced.

For the recording of colored originals which transmit or reflect colored light, the recording layer may contain as lightabsorbing ingredient a substance or mixture of substances, which absorbs only light of a part of the visible spectrum and converts that light into heat. Preferably (a) substance(s) (is) are incorporated that abs0rb(s) light of one of the primary colors (red, green, blue) or subtractive colors (cyan, magenta, yellow).

Substances that absorb visible light in a part of the visible spectrum and wherein absorbed light energy is converted into heat are, e.g., dyes belonging to the classes of the azo, triarylmethane, xanthene, acridine, methine, azine, phthalocyanine, anthraquinone and allied dyes.

Said substances can be used in dispersed and/or dissolved state, and when used in dispersed form preferably have a grain size lower than 0.1

The amount of said substances required in the recording layer wherein heat is generated by means of absorbed electromagnetic radiation depends on the desired heat-sensitivity of such material, the intensity of the irradiation to be employed and the yield of heat resulting from the irradiation of said substances.

ln recording materials considered above the light-absorbing substance (visible and/or infrared light) is distributed all over the recording layer, e.g., is dissolved or dispersed in the hydrophilic binder and/or in the thermoplastic hydrophobic particles of recording layers wherein they are present. When such a recording material is used a heat pattern can be produced in the recording layer by exposing it to any pattern of radiation. A recording process according to the invention can be preformed, however, by nondifferentially exposing the recording material over its entire extent to electromagnetic radiation, if the recording layer contains visible light and/or infrared-absorbing substance(s) distributed therein according to a predetermined pattern, which itself represents the information to be recorded.

A predetermined distribution of radiation-absorbing sub stance can be achieved by preparing a heat-sensitive recording layer comprising a light-sensitive material from which radiation-absorbing substance can be formed in situ in selected areas under the influence of light. After exposure of such a material to a light pattern, followed if required by the nature of the light-sensitive composition by a suitable development, it is ready for the heat-generating exposure.

Preferably light-sensitive silver halide is used as the substance from which imagewise infrared-absorbing silver can be formed.

An alternative way of bringing about an information distribution of infrared-absorbing substance in the recording material is to form a silver image in situ from complexed silver halide formed in or introduced into the recording material and deriving from unexposed portions of an informationwise exposed silver halide emulsion layer as known per se in silver salt diffusion transfer processes. The silver halide applied for forming the infrared-absorbing silver image may be of the type suitable for forming a negative image or a direct positive image according to the requirements made to the reproduction. The silver halide is preferably combined in the recording material with a suitable developing agent, e.g., hydroquinone, so that the development can be carried out with a so-called activating bath which is an alkaline aqueous solution containing no developing agent. On nondifferentially exposing the recording layer containing the silver image with infrared and/or visible light of sufficient intensity, the surface layer is modified in permeability in correspondence with the silver image portions.

The layer (interlayer) or support beneath the recording layer, if an image has to be formed therein is preferably liquid permeable or porous so that it can absorb a liquid consisting of or comprising a substance or mixture of substances yielding the desired physical and/or chemical change. The support, however, is preferably only porous or permeable at the side coated with the recording layer.

Suitable water permeable supports are, e.g., paper supports, and supports of modified cellulose, e.g., hydrated cellulose and ethylcellulose.

The recording layer may be applied onto a nonpermeable interlayer, e.g., support when the image has to be formed by etching or by disintegration of the interlayer or support. Thus, the interlayer may be a metal layer and the support a metal sheet. The interlayer may be a bimetal layer consisting of a layer of a hydrophilic metal (e.g., chromium) applied to a layer of a hydrophobic metal e.g., copper. Such an arrangement is used in the preparation of planographic printing masters.

In order to reduce the solubility, more particularly the solubility in water of colloids or resins applied in the interlayer, a hardening or curing may be carried out but preferably not to such an extent that the water permeability is destroyed.

The hardening or curing agent should be selected for each colloid or polymer. For example polyvinyl alcohol can be insolubilized by dimethylolurea; sodium alginate or sodium polyacrylate can be insolubilized with a solution of zinc chloride, and gelatin can be reduced in water solubility with chrome alum or an aldehyde such as formaldehyde and glyoxal.

The liquid used for effecting the chemical and/or physical change in the interlayer or support is called hereinafter developing liquid."

According to one embodiment of the present invention in the support or a layer beneath the surface recording layer, a visible image is formed by means of an aqueous developing liquid containing substances that penetrate through the water permeable portions of the surface layer after the imagewise exposure to heat. Such substances may be oxidizing agents, e.g., for the oxidation of leuco dyes, reducing agents, e.g. for the reduction of metal salts to metal, dyes, reaction components for the formation of dyes, and catalysts, e.g., for a hardening or color reaction.

According to a special embodiment the interlayer contains fogged light-sensitive silver halide which is imagewise reduced to silver by developing substances penetrating into the permeable portions of the imagewise heated surface recording layer.

instead of incorporating light-sensitive silver halide in the interlayer it may be applied to the support of the recording layer. Coating of the light-sensitive silver halide may be carried out in a nonconventional way, e.g., by a vacuum-evaporation technique.

Image formation may also proceed by the silver halide com plex diffusion transfer process with an interlayer or support containing developing nuclei suited for said transfer process. Thus, silver halide present in the nonimpermeabilized portions of the surface recording layer is transferred by diffusion in complexed form in the interlayer or on the support wherein or whereon it is developed under the initiating action of the said developing nuclei.

For use in an etching development the support may be metallized. According to the purpose the imagewise etched support can serve as printing master, e.g., planographic printing master, or printed circuit.

According to another embodiment of the present invention a hydrophilic support or layer beneath the surface recording layer is made imagewise hydrophobic by a substance or composition selectively penetrating the imagewise heated recording layer, e.g., a gelatin interlayer is imagewise hydrophobized by means of tannic acid. After removal of the surface layer a planographic printing master is left, which can be used for hydrotype printing as well as for classical planographic or offset printing with a fatty ink and a damping system.

According to a special embodiment, which is suited for the reproduction of a multicolor original on a single support the heat-sensitive surface recording layer by imagewise heating obtains an imagewise differentiation in water permeability in correspondence with one of the separation images in a primary color (blue, green or red) of the original, and after its development with the corresponding complementary dye (yellow, magenta, or cyan) is removed and replaced by a second heat-sensitive surface layer which in its turn is selectively heated in correspondence with a second separation image in another primary color of the original, and after its development with the corresponding complementary dye is removed and replaced in its turn by a third heat-sensitive surface recording layer, which at last after its selective heating in correspondence with the third primary color of the original is removed too after its development with the corresponding complementary dye. The application. of the said heat-sensitive surface layers to the complementary dye-receiving interlayer may proceed by conventional coating techniques. As special coating techniques spray-coating and coating by stripping as explained in example 2 are used.

In order to obtain an impermeabilization in correspondence with the primary color part images of the multicolor original, the heat-sensitive surface recording layer containing a heatgenerating pigment or dye absorbing light of one of the primary color regions (blue, green or red) may be exposed in transmission or reflection to said multicolor original by using the right filter transmitting only the light corresponding to the color of the primary color parts to be reproduced. Preferably, however, first separate black-and-white negative transparencies are produced from the multicolor original which negative transparencies correspond with the primary color part images contained in said original and may be considered as a selection internegative" in the exposure of the heat-sensitive surface recording layer.

In that case the recording layer preferably contains dark colored pigments, which absorb visilble and/or infrared light and transform absorbed light into heat. The exposures through the three separate transparencies are to be carefully carried out in register. The successive developments are carried out in such a way that the colors of the original are reproduced by the mixture of dyes absorbed in the interlayer or support from three developing solutions, which respectively contain a yellow, magenta and cyan dye, so that according to the subtractive color reproduction technique a true color copy of the multicolor original is obtained. The dye-absorbing support or interlayer preferably contains a mordanting agent for the applied dye, which mordanting agent prevents lateral diffusion. The use of mordanting agents in the dying of gelatin and inhibition printing is described by P. Glafkides, Photographic Chemistry, Vol. ll, p. 689-701 (1960) Fountain Press, London.

Suitable polymeric mordanting agents for the Technicolor process are described in the United Kingdom Pat. No. 954,206.

Particularly suited mordants for triphenylmethane dyes are found in the class of ferrocyanides such as copper ferrocyanide, complex metallic salts of heteropolyacids such as silicotungstates, phosphotungstates, and chlorostannates.

lnstead of a dyestuff absorbing a part of the visible light a UV-absorbing compound can be imagewise absorbed in the interlayer or support. As an alternative, a compound may be allowed to diffuse in the interlayer or support, which by reaction with a substance or substances contained therein forms an ultraviolet absorbent, or a substance, e.g., silver, forming a barrier to the penetration of ultraviolet light.

The recording layer wherein the permeability pattern is created is preferably removed by a mechanical action, e.g., rubbing in wet state by using a liquid which is preferably a good solvent for the hydrophilic binder of the surface layer if such a binder is present. The liquid applied in the removal is called hereinafter processing liquid." The processing liquid may contain all kinds of ingredients improving the removal of the surface layer by a chemical or physical attack. In that respect reference is made, e.g., to softening agents for the binder, a base, acid or swelling agent improving the solubility r swellability ofthe binder in the processing liquid.

As rubbing element a cotton pad or fast revolving friction roller coated e.g., with foamed rubber can be used.

Obviously, in the preferred recording and reproduction system, wherein the recording surface layer containing finely dispersed or dissolved substances absorbing infrared and/or visible light is imagewise heated by imagewise exposure to light, the intensity of the light energy to which the light-absorbing material is exposed constitutes an important factor. A surface recording layer that does not show a sufficient physical differentiation in water permeability after a given exposure may nevertheless be quite suitable when used with an exposure of increased level, or a certain integral preheating.

Certain originals have light-absorbing image markings and if such markings are in contact with the recording material (and particularly if they are in contact with the recording layer) during the exposure, the exposure should be of such short duration that the recording layer does not become affected in a way which prevents the required image formation by heat conductance from such markings. According to a preferred embodiment the light exposure does not exceed l0 sec. and is comprised between l0 and sec. Lamp structures and systems capable of providing short and very high intensity exposure are commercially available.

Light sources with a high radiation intensity and relatively short exposure time are the so-called flashlamps and more particularly the gas discharge flashlamps.

According to a preferred exposure technique use is made of a xenon gas discharge lamp, which can supply an energy of 300-] ,000 watt.sec in a period of l0 to 10" seconds. Electromagnetic radiation emitted in the range of 300 to l,000p., is preferably used.

According to a preferred arrangement the gas discharge lamp is in the form of a thin tube fitted in a hollow glass cylinder, in order to make possible a uniform exposure of the recording material applied together with the original to the periphery of the cylinder.

More details about such a gas discharge lamp suitable for use in carrying out the invention are given in Belgian Pat. No. 664.868 and in the published Dutch Pat. application 6,606,719, which documents should also be read in conjunction herewith and are deemed to form part of the present disclosure.

Evidently gas discharge lamps with a lower energy output may be used if the emitted energy is focused onto a relatively small heat-sensitive area. 50, eg, a gas discharge lamp with an energy output of 40 watt.sec. is suited for copying 6 cm.X6 cm. and 6 cm.X9 cm. originals on heat-sensitive materials as described in the present invention. For materials having an optical density of at least 1 resulting from the presence of the light-absorbing substances in the recording layer, in practice a light energy of 0.3 watt.sec. per sq.cm. will suffice for the desired image differentiation (water-impermeabilization). The recording material need not be exposed simultaneously in all parts. The exposure may be progressive in one continuous step or in successive intermittent steps. Thus, the recording material may be scanned with an imagewise modulated lightspot of high intensity, e.g., a laser beam, or may be progressively exposed through a slit wherein, e.g.. copying light of a continuously emitting tubelike radiation source is focused.

A great advantage of the thermocopying process with visible light is that it can be used to record originals having image markings which are not infrared absorbing and nonheat-conductive. When carrying out the invention in its preferred embodiments, very sharp images of printed matter can be obtained.

During the exposure through an original (transmission printing) the original is placed between the radiation source and the recording material. The heat-sensitive recording layer may be placed directly in contact with the original or with an intervening transparent sheet or layer. The recording material comprising the recording layer on a support may be located with its support against the original. in that case the support and interlayer must transmit visible light, and the support is preferably nonheat-conductive.

During reflectographic exposure the recording material, which in this case must transmit printing light, is placed between the radiation source and the original. The original (negative or positive) comprises areas reflecting copying light or is a transparency placed in contact with or in near proximity to a surface that reflects light.

The following examples illustrate the present invention.

EXAMPLE I A polyethylene terephthalate support of 0.1 mm. thickness provided with a subbing layer for gelatin was coated with a layer of 50 g./sq.m. from the following composition:

10 percent aqueous solution of gelatin 935 g.

l0 percent aqueous solution of saponine 30 g.

3 percent aqueous solution of the sodium salt of the 30 condensation product of oleic acid and methyltaurine 4 percent aqueous solution of formaldehyde 5 8- After solidification, a heat-sensitive layer was applied thereto from the following composition pro rata of 36 g./sq.m.:

l0 percent aqueous gelatin solution I00 g.

40% aqueous dispersion of polyethylene having a particle size of less than 0,] y. and an average molecular weight comprised between 15,000 and aqueous carbon dispersion containing per I00 q, 53 g.

of carbon black. 23 g. of water. l8 g. of glycol and 6 g. of nonylphenoxypolyethylene oxide 20 g.

5% aqueous solution of sodium tetradecylsulphateso g.

water 645 g.

After drying, the recording material was brought with its surface layer in contact with printed text markings of an original and reflectographically exposed with a xenon gas discharge tube, which irradiated the surface of the recording layer with an energy of 0.4 watt.sec./sq.cm. in 3.10 sec.

Subsequently, the exposed material for 10 seconds was dipped in a percent aqueous solution of tannic acid and thereupon for 20 seconds in a 2 percent aqueous sodium carbonate solution.

After removal of the surface layer with a cotton pad in running water a planographic printing master was obtained of which the hydrophobic areas constituted a laterally reversed image of the printed text. That master yielded legible copies in direct printing (no offset) with a fatty ink.

EXAMPLE 2 Material A A polyethylene terephthalate support of 0.1 mm. thickness provided with a subbing layer for gelatin was coated pro rata of 40 g./sq.m. with the following composition, which had been acidified with sulfuric acid to pH 4.5:

% aqueous solution ofgelatin 300 l0; aqueous solution of POLYMIN P (registered trademark for a 50% by weight aqueous solution of polyethyleneimine marketed by Badische Anilin- 8r. Soda-Fabrik A.G., Ludwigshafen/Rh) as mordanting agent 25 g.

4% aqueous solution of formaldehyde 5 g.

The coated layer was dried.

Material B Onto a cellulose triacetate support of 0.14 mm. thickness a heat-sensitive layer was coated from the following composition pro rata of removing 30 g./sq.m.:

l0; aqueous solution of gelatin I00 g.

40)? aqueous dispersion of olyethylene having a particle size of less than 0.l and an average molecular weight comprised between 15,000 and aqueous carbon dispersion containing pro l00 g., 53

g. of carbon black, 23 g. of water, 18 g. of glycol and 6 g. of nonylphenoxypolyethylene oxide l5 g.

0.571' aqueous solution of sodium tetradecylsulphate 40 g.

water 700 g,

The coated layer was solidified and dried.

In order to obtain a three-color reproduction ofa multicolor original, from which screened black-and-white separation negatives (silver image transparencies) corresponding with the three complementary colors (yellow, magenta, and cyan) had been prepared, the following procedure was applied. The material A was moistened with water and in contact with the heat-sensitive layer of material B led between two pressure rollers and after 2 seconds peeled apart therefrom so that the heat-sensitive layer was transferred to material A by stripping.

After drying, the transferred heat-sensitive surface layer of the recording material was contacted with the screened negative black-and-white separation transparency corresponding with the yellow parts of the original, and exposed therethrough by means of a xenon gas discharge tube irradiating the recording layer with an energy of 0.8 watt.sec./sq.cm. in 3.10 second.

ln correspondence with the nonexposed areas, the dye was fixed in the interlayer containing polyethyleneimine. After 1 min., of rinsing with plain water, the surface recording layer was completely rubbed off in wet state with a cotton pad. A yellow positive part image of the original was obtained.

To the said layer containing the yellow separation image a heat-sensitive surface layer as already defined was applied by the stripping technique as described above, and the said layer was flash-exposed through the screened negative black-andwhite separation transparency corresponding to the cyan parts of the original, The exposed solution material was dipped into a 2 percent aqueous solution of the compound having the f0rmula:

After 1 min. of rinsing and removal of the surface recording layer as already described, a positive subtractive three-color transparency of the original was obtained.

EXAMPLE 3 A polyethylene terephthalate support of 0.1 mm. thickness provided with a subbing layer for gelatin was coated pro rata of 60 g./m. in daylight with a gelatin silver chloride emulsion containing 50 g. of gelatin/liter.

After solidification and drying, a heat-sensitive layer was .aL, tar

10% aqueous solution of poly(N-vinylpyrrolidone) (average molecular weight 10,000) 50 g.

40% aqueous dispersion of polyethylene having a particle size of less than 0.1 and an average molecular weight comprised between 15.000 and aqueous carbon dispersion containing pro 100 g. 53 g. of carbon. 23 g. ofwater. 18 g. of glycol and 6 g. of nonylphenoxy polyethylene oxide 4 g.

4% aqueous solution of formaldehyde 10 g.

5% aqueous solution of sodium tetradecylsulphate water 330 ccs.

After drying, the recording layer was exposed in contact with and behind a transparent screen image (silver image) by means of a xenon gas discharge lamp, which irradiated the heat-sensitive layer with an energy of 0.8 watt.sec. per sq.cm. in sec.

The exposed material first was dipped in a common silver halide developing solution and thereupon in a stop bath. On the nonexposed parts corresponding with the screen dots of the original the surface layer was "101 impermeabilized, and consequently a silver image was developed in the interlayer.

After rubbing off the heat-sensitive surface layer in running water with a cotton pad and fixing the silver image in the inter layer by removing the undeveloped silver halide, a positive silver image of the original was obtained.

EXAMPLE 4 The recording material described in example 3 was reflectographically exposed to a line original with a xenon gas discharge bulb, which irradiated the surface recording layer with an energy of 0.4 watt.sec. per sq.cm.

The processing was the same as that described in example 3. A positive image of the original was obtained, which was legible through the transparent support EXAMPLE 5 To a polyethylene terephthalate support of 0.1 mm. thickness provided with a subbing layer for gelatin the following solution was applied in a proportion of 40 g./sq.m. after it has been brought to pH 4.5 by means of sulfuric acid:

10; aqueous gelatin solution 300 ccs.

10% aqueous solution of POLYMlN P (registered trademark) as mordanting agent cos. 4% aqueous solution of formaldehyde 5 ccs.

The layer applied was dried at C. Onto this layer a heatsensitive layer was coated from the following composition pro rata of 30 g./sq.m.:

10% aqueous gelatin solution 100 ccs.

40' aqueous dispersion of polyethylene having an average particle size ofO.l and a molecular weight comprised between 15.000 and 30,000 160 ccs.

water 700 ccs.

4% aqueous solution of formaldehyde 4O ccs.

After drying, the polyethylene-containing layer of the material was brought into contact with a printed text and exposed to infrared light. Then this imagewise heated material was dipped into a 2.5 percent aqueous solution of metanil yellow as UV-absorbing compound. This dye penetrated into the layer in correspondence with the nonheated areas. The areas of the recording layer corresponding with the infrared-absorbing image markings of the original were made impermeable by heating and absorbed no dye. in this way a UV-absorbing negative was obtained from which the recording layer was eliminated by wetting with water and by rubbing.

EXAMPLE 6 Example 5 was repeated with the difference, however, that the gelatin in the heat-sensitive layer was replaced by polyvinylpyrrolidone. The heat-sensitive layer could be washed away with cold water and by rubbing.

lclaim:

1. A method of recording information which comprises (1) applying a pattern of heat according to the information to be recorded to a recoding material having a substrate adapted to become colored when contacted with an aqueous solution of a colorant and superimposed upon said substrate a waterpermeable heat-sensitive layer comprised essentially of a dispersion of solid hydrophobic thermoplastic polymer particles in a continuous phase of a hydrophilic binder in a weight ratio greater than 1:1, the amount of such heat being sufficient to render the heated areas of said heat-sensitive layer substantially water impermeable; (2) contacting the thus exposed recording material with an aqueous solution of a colorant, said solution penetrating the unexposed and permeable areas of said heat-sensitive layer and imparting color to the substrate therebeneath while being excluded from the exposed and impermeabilized areas of said layer; and (3) thereafter removing said heat-sensitive layer in entirety from said recording material to expose the substrate bearing thereon a colored reproduction of the nonheated areas of said material.

2. The method of claim 1 wherein said heat-sensitive layer also includes dispersed throughout said binder finely divided particles of a pigment or dye absorbing electromatic radiation and converting the same into heat, and said heat-sensitive layer is exposed to an image of said radiation according to said information of such intensity and duration as to create a heat pattern internally within the image areas thereof.

3. The method of claim 2 wherein said radiation is within the range of visible to infrared light.

4. A method according to claim 1, wherein said particles are wax or waxlike particles.

5. A method according to claim 1, wherein said binder is water soluble.

6. A method according to claim 5, wherein the binder mainly contains gelatin of the type becoming more soluble in water when heated.

7. A method according to claim 1, wherein the recording layer consists of polyvinyl alcohol containing at least percent of vinyl alcohol units and (a) light-absorbing substance(s) distributed therein.

8. A method according to claim 3, wherein the heat-sensitive layer contains carbon particles as the particles absorbing infrared radiation and visible light.

9. A method according to claim 3, wherein the heat-sensitive layer contains silver as the particles absorbing infrared radiation and visible light.

10. A method according to claim 3, wherein the heat-sensitive layer is exposed to infrared and/or visible light for a period of less than l0 see. with an intensity of at least 0.1 watt.sec./sq.cm.

11. A method according to claim 10, wherein the exposure is carried out by means of a flashlamp exposing the recording layer within a period of 10 to 10 sec.

12. A method according to claim 1, wherein the said hydrophobic thermoplastic polymer particles are present in the recording layer in a weight ratio of at least 3:1.

13. A method according to claim 1, wherein the hydrophobic thermoplastic polymer particles are polyethylene particles dispersed in gelatin and/or poly(N-vinylpyrrolidone).

14. A method according to claim 1, wherein said polymer particles size from 0.01; to 50p.

15. A method according to claim 1, wherein the said liquid is a solution ofa dyestuff, or a dye-forming component.

116. A method according to claim ll, wherein the heat-sensitive layer is removed in entirely by rubbing it while in a wet condition.

17. A method for recording a multicolor original by means of a recording material containing a water-permeable interlayer and external heat-sensitive layer comprised essentially of a dispersion of solid thermoplastic hydrophobic particles in a hydrophilic binder in a ratio by weight greater than lzl, said binder also having dispersed therein black or dark-colored pigments or dyes, which absorb visible and/or infrared light and convert absorbed light into heat, said method comprising the steps of:

l. flash exposing for an exposure time of less than sec the external layer to a screened black-and-white silver separation negative of a primary color separation image of the multicolor original to be reproduced;

2. developing the recording material by an aqueous solution penetrating the portions of the external layer remaining permeable after said exposure, which solution contains a dissolved dyestuff corresponding with the color to be reproduced;

3. removing the external layer in entirety by rubbing it while wet;

4. applying a new nonexposed external layer having said composition to the developed interlayer containing already a monocolor dyestuff image;

5. flash-exposing the new external layer as in step (1) but wet;

. applying a new nonexposed external layer of said composition to the developed interlaye'r already containing a bicolor dyestuff image;

9. flash-exposing the new external layer as in step (I) but through a screened black-and-white silver separation negative corresponding with a third color separation image of the multicolor original to be reproduced;

10. developing the recording material by an aqueous solution penetrating the portions of the recording layer remaining permeable after said exposure, which solution contains a dissolved dyestuff corresponding with the color to be reproduced, and

ll. removing the external layer in entirety by rubbing it while wet, and drying the recording material now containing a tricolor dyestuff image of the original.

. removing the external layer in entirety by rubbing it while UNITED STATES PATENT oFFicE CERTIFICATE OF CORRECTION Patent No. 3 615 423 Dated October 26 1971 Inventor) Marcel Nicolas VRANCKEN It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 12, Claim 1, line 14, change "recoding" to recording I: Column 12, Claim 10, line 61, change 10 to l0 Column 12, Claim 11, line 65, change "10 to 10 to Column 13, Clalm 17, line 13, change l0 to l0 Signed and sealed this 251m day of Apr 1972.

(SEAL) Arte-st:

EDWARD I-'I=FLETCHEB,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents RM po'mba 0-69) USCOMM-DC BO376-P59 i U.S GOVQIINMENT PIHNTING OFFECE: 196D 0*.16-33 

2. The method of claim 1 wherein said heat-sensitive layer also includes dispersed throughout said binder finely divided particles of a pigment or dye absorbing electromatic radiation and converting the same into heat, and said heat-sensitive layer is exposed to an image of said radiation according to said information of such intensity and duration as to create a heat pattern internally within the image areas thereof.
 2. developing the recording material by an aqueous solution penetrating the portions of the external layer remaining permeable after said exposure, which solution contains a dissolved dyestuff corresponding with the color to be reproduced;
 3. The method of claim 2 wherein said radiation is within the range of visible to infrared light.
 3. removing the external layer in entirety by rubbing it while wet;
 4. A method according to claim 1, wherein said particles are wax or waxlike particles.
 4. applying a new nonexposed external layer having said composition to the developed interlayer containing already a monocolor dyestuff image;
 5. flash-exposing the new external layer as in step (1) but through a screened black-and-white silver separation negative corresponding with a second color separation image of the multicolor original to be reproduced;
 5. A method according to claim 1, wherein said binder is water soluble.
 6. A method according to claim 5, wherein the binder mainly contains gelatin of the type becoming more soluble in water when heated.
 6. developing the recording material by an aqueous solution penetrating the portions of the external layer remaining permeable after said exposure, which solution contains a dissolved dyestuff corresponding with the color to be reproduced, and
 7. A method according to claim 1, wherein the recording layer consists of polyvinyl alcohol containing at least 95 percent of vinyl alcohol units and (a) light-absorbing substance(s) distributed therein.
 7. removing the external layer in entirety by rubbing it while wet;
 8. applying a new nonexposed external layer of said composition to the developed interlayer already containing a bicolor dyestuff image;
 8. A method according to claim 3, wherein the heat-sensitive layer contains carbon particles as the particles absorbing infrared radiation and visible light.
 9. flash-exposing the new external layer as in step (1) but through a screened black-and-white silver separation negative corresponding with a third color separation image of the multicolor original to be reproduced;
 9. A method according to claim 3, wherein the heat-sensitive layer contains silver as the particles absorbing infrared radiation and visible light.
 10. developing the recording material by an aqueous solution penetrating the portions of the recording layer remaining permeable after said exposure, which solution contains a dissolved dyestuff corresponding with the color to be reproduced, and
 10. A method according to claim 3, wherein the heat-sensitive layer is exposed to infrared and/or visible light for a period of less than 10 1 sec. with an intensity of at least 0.1 watt.sec./sq.cm.
 11. removing the external layer in entirety by rubbing it while wet, and drying the recording material now containing a tricolor dyestuff image of the original.
 11. A method according to claim 10, wherein the exposure is carried out by means of a flashlamp exposing the recording layer within a period of 10 2 to 10 5 sec.
 12. A method according to claim 1, wherein the said hydrophobic thermoplastic polymer particles are present in the recording layer in a weight ratio of at least 3:1.
 13. A method according to claim 1, wherein the hydrophobic thermoplastic polymer particles are polyethylene particles dispersed in gelatin and/or poly(N-vinylpyrrolidone).
 14. A method according to claim 1, wherein said polymer particles size from 0.01 Mu to 50 Mu .
 15. A method according to claim 1, wherein the said liquid is a solution of a dyestuff, or a dye-forming component.
 16. A method according to claim 1, wherein the heat-sensitive layer is removed in entirely by rubbing it while in a wet condition.
 17. A method for recording a multicolor original by means of a recording material containing a water-permeable interlayer and external heat-sensitive layer comprised essentially of a dispersion of solid thermoplastic hydrophobic particles in a hydrophilic binder in a ratio by weight greater than 1:1, said binder also having dispersed therein black or dark-colored pigments or dyes, which absorb visible and/or infrared light and convert absorbed light into heat, said method comprising the steps of: 